Even if you're covered by two insurance plans, you can't get double reimbursement for the same medical bills. If one of your insurers is Medicare, government rules determine how the two coverages interact.

Coordination of Benefits

Whenever you have two sources of health insurance, the insurers have to coordinate benefits. One of them becomes the primary insurer and pays first, up to the policy's limits of coverage. The secondary insurer than takes over and pays any remaining expenses, again up to the limits in your policy. Depending on the policy and the bills you're submitting, you still may have out-of-pocket expenses.

Secondary insurance is not the same as supplemental insurance. A secondary insurer could be Medicaid, your employer's health coverage or your spouse's workplace coverage, for instance. Supplemental insurance, also called Medigap, is specifically tailored to cover copayments, coinsurance, and deductibles that Medicare doesn't pay, and possibly services Medicare doesn't reimburse. Medigap is designed not to cover the same expenses as Medicare.

Tip

You must sign up for Medicare Part A and B to qualify for a Medigap supplemental policy. Some private insurers require you sign up for Medicare Part B, if you're eligible, before they serve as secondary payer. Medicare Part A pays for stays in hospitals and similar facilities; Part B covers doctor visits and treatments for preventive, diagnostic and other medically necessary services.

Primary or Secondary

The Centers for Medicare and Medicaid Services list some examples of how Medicare and your other insurer coordinate benefits:

If you're over 65 and covered by an employee plan — whether through your employer or your spouse's job — Medicare is the secondary payer. An exception occurs if the employer has fewer than 20 employees. Then Medicare becomes primary.

When you have coverage under COBRA — a federal policy that allows you to keep workplace insurance for 18 months after you leave the job — Medicare pays first.

If you're covered by Medicaid as well as Medicare, Medicare pays first.

How It Works

When you give your insurance coverage to your doctor, hospital or other medical caregiver, you provide information for both Medicare and your other insurance. The doctor submits the claim. If you have to pay up front for a service, you'll get a reimbursement check later.

Primary and secondary status has nothing to do with which insurer pays soonest. If your private insurance is primary but takes a long time to pay the claim, the doctor may submit the same bill to Medicare. The agency can send you a conditional payment. Later, when you receive your payment from the primary insurer, you reimburse Medicare accordingly.

About the Author

A graduate of Oberlin College, Fraser Sherman began writing in 1981. Since then he's researched and written newspaper and magazine stories on city government, court cases, business, real estate and finance, the uses of new technologies and film history. Sherman has worked for more than a decade as a newspaper reporter, and his magazine articles have been published in "Newsweek," "Air & Space," "Backpacker" and "Boys' Life." Sherman is also the author of three film reference books, with a fourth currently under way.